Toxic mechanism of cadmium exposure on cardiac tissue

The presence of toxic substances in the workplace environment requires systematic evaluation of exposure and health status in exposed subjects. Cadmium is a highly toxic element found in water. Although free mediated cellular damage and reactive oxygen species (ROS), had been theorized as contributing to the cadmium mechanism of toxicity, and recent investigations have established that free radicals may be important contributors to cardiac dysfunction, there is little information on the effect of cadmium exposure on markers of oxidative stress in cardiac tissue. Cadmium exposure (Cd2+ - 100 mg/1-from CdCl2) in drinking water, during 15 days, significantly increased lipoperoxide and decreased the activities of superoxide dismutase and glutathione peroxidase. No alterations were observed in catalase activity in heart of rats with cadmium exposure. We also observed decreased glycogen and glucose concentration and increased total lipid content in cardiac tissue of rats with cadmium exposure. The decreased activities of alanine transaminase and aspartate transaminase reflected decreased metabolic protein degradation, and increased lactate dehydrogenase activity was related with increases in capacity of glycolysis. Since the metabolic pathways were altered by cadmium exposure, we can conclude that Cd2+ exposure induced ROS and initiate some series of events that occur in the heart and resulted in metabolic pathways alterations.

Teor mineral e capacidade antioxidante em chás e infusões

Mestrado em Engenharia Química – Ramo Optimização Energética na Indústria Química

Measurement of lead concentration in biological tissues by atomic spectroscopy techniques

Dissertation for the degree of Doctor of Philosophy in Physics

Treg-therapy allows mixed chimerism and transplantation tolerance without cytoreductive conditioning.

Establishment of mixed chimerism through transplantation of allogeneic donor bone marrow (BM) into sufficiently conditioned recipients is an effective experimental approach for the induction of transplantation tolerance. Clinical translation, however, is impeded by the lack of feasible protocols devoid of cytoreductive conditioning (i.e. irradiation and cytotoxic drugs/mAbs). The therapeutic application of regulatory T cells (Tregs) prolongs allograft survival in experimental models, but appears insufficient to induce robust tolerance on its own. We thus investigated whether mixed chimerism and tolerance could be realized without the need for cytoreductive treatment by combining Treg therapy with BM transplantation (BMT). Polyclonal recipient Tregs were cotransplanted with a moderate dose of fully mismatched allogeneic donor BM into recipients conditioned solely with short-course costimulation blockade and rapamycin. This combination treatment led to long-term multilineage chimerism and donor-specific skin graft tolerance. Chimeras also developed humoral and in vitro tolerance. Both deletional and nondeletional mechanisms contributed to maintenance of tolerance. All tested populations of polyclonal Tregs (FoxP3-transduced Tregs, natural Tregs and TGF-beta induced Tregs) were effective in this setting. Thus, Treg therapy achieves mixed chimerism and tolerance without cytoreductive recipient treatment, thereby eliminating a major toxic element impeding clinical translation of this approach.

Preliminary evaluation of acid mine drainage in Minas Gerais State, Brazil

Mining in the State of Minas Gerais-Brazil is one of the activities with the strongest impact on the environment, in spite of its economical importance. Amongst mining activities, acid drainage poses a serious environmental problem due to its widespread practice in gold-extracting areas. It originates from metal-sulfide oxidation, which causes water acidification, increasing the risk of toxic element mobilization and water resource pollution. This research aimed to evaluate the acid drainage problem in Minas Gerais State. The study began with a bibliographic survey at FEAM (Environment Foundation of Minas Gerais State) to identify mining sites where sulfides occur. Substrate samples were collected from these sites to determine AP (acidity potential) and NP (neutralization potential). The AP was evaluated by the procedure of the total sulfide content and by oxygen peroxide oxidation, followed by acidity titration. The NP was evaluated by the calcium carbonate equivalent. Petrographic thin sections were also mounted and described with a special view to sulfides and carbonates. Based on the chemical analysis, the acid-base accounting (ABA) was determined by the difference of AP and NP, and the acid drainage potential obtained by the ABA value and the total volume of material at each site. Results allowed the identification of substrates with potential to generate acid drainage in Minas Gerais state. Altogether these activities represent a potential to produce between 3.1 to 10.4 billions of m³ of water at pH 2 or 31.4 to 103.7 billions of m³ of water at pH 3. This, in turn, would imply in costs of US$ 7.8 to 25.9 millions to neutralize the acidity with commercial limestone. These figures are probably underestimated because some mines were not surveyed, whereas, in other cases, surface samples may not represent reality. A more reliable state-wide evaluation of the acid drainage potential would require further studies, including a larger number of samples. Such investigations should consider other mining operations beyond the scope of this study as well as the kinetics of the acid generation by simulated weathering procedures.

Growth of seedlings of pigeon pea (Cajanus cajan (l.) millsp), wand riverhemp (Sesbania virgata (cav.) pers.), and lead tree (Leucaena leucocephala (lam.) de wit) in an arsenic-contaminated soil

Phytoremediation strategies utilize plants to decontaminate or immobilize soil pollutants. Among soil pollutants, metalloid As is considered a primary concern as a toxic element to organisms. Arsenic concentrations in the soil result from anthropogenic activities such as: the use of pesticides (herbicides and fungicides); some fertilizers; Au, Pb, Cu and Ni mining; Fe and steel production; coal combustion; and as a bi-product during natural gas extraction. This study evaluated the potential of pigeon pea (Cajanus cajan), wand riverhemp (Sesbania virgata), and lead tree (Leucaena leucocephala) as phytoremediators of soils polluted by As. Soil samples were placed in plastic pots, incubated with different As doses (0; 50; 100 and 200 mg dm-3) and then sown with seeds of the three species. Thirty (pigeon pea) and 90 days after sowing, the plants were evaluated for height, collar diameter and dry matter of young, intermediate and basal leaves, stems and roots. Arsenic concentration was determined in different aged leaves, stems and roots to establish the translocation index (TI) between the plant root system and aerial plant components and the bioconcentration factors (BF). The evaluated species showed distinct characteristics regarding As tolerance, since the lead tree and wand riverhemp were significantly more tolerant than pigeon pea. The high As levels found in wand riverhemp roots suggest the existence of an efficient accumulation and compartmentalization mechanism in order to reduce As translocation to shoot tissues. Pigeon pea is a sensitive species and could serve as a potential bioindicator plant, whereas the other two species have potential for phytoremediation programs in As polluted areas. However, further studies are needed with longer exposure times in actual field conditions to reach definite conclusions on relative phytoremediation potentials.

Distribuição de Zn, Pb, Ni, Cu, Mn e Fe nas frações do sedimento superficial do Rio Cachoeira na região sul da Bahia, Brasil

The metal distribution in the surface sediment fractions of the Cachoeira River was evaluated based on the fractionation method using a five-step sequential extraction. The determination of metals was made by flame atomic absorption spectrophotometry (F AAS). Zn, Pb and Cu exhibit higher concentrations in the residual fraction of the sediment from sites that receive discharges from urban and industrial zones. High levels of Ni (60 ± 1 to 447 ± 9 µg L-1) were found in the river water, which may be detrimental to the "health" of rural communities that utilize the river water for domestic purposes without treatment.

Development of the Food List for a Brazilian Total Diet Study

The objective of this paper is to establish a methodology for the Food List for the southeastern region of Brazil, according to the Total Diet Study (TDS) harmonized methodology at international level. The Food List can provide data for a further TDS with evaluation of essential and toxic element dietary intakes by food analysis in laboratories. The food consumption data source used was from 2008-2009 Household Budget Survey, by the Brazilian Institute of Geography and Statistics. The Food List was composed of 82 food items grouped into 19 food groups. It reflects 100% of the daily individual food consumption inside and outside Brazilian southeastern population households. According to the recommendation that each country should carry out their own TDS and the TDS methodology used, the Food List construction can contribute to the Food List of other Brazilian regions and other countries, besides allowing the TDS development. Additionally, the Food List showed the typical diet for the southeastern region of Brazil.

Cobalt incorporation in calcite: Thermochemistry of (Ca,Co)CO3 solid solutions from density functional theory simulations

The incorporation of cobalt in mixed metal carbonates is a possible route to the immobilization of this toxic element in the environment. However, the thermodynamics of (Ca,Co)CO3 solid solutions are still unclear due to conflicting data from experiment and from the observation of natural ocurrences. We report here the results of a computer simulation study of the mixing of calcite (CaCO3) and spherocobaltite (CoCO3), using density functional theory calculations. Our simulations suggest that previously proposed thermodynamic models, based only on the range of observed compositions, significantly overestimate the solubility between the two solids and therefore underestimate the extension of the miscibility gap under ambient conditions. The enthalpy of mixing of the disordered solid solution is strongly positive and moderately asymmetric: calcium incorporation in spherocobaltite is more endothermic than cobalt incorporation in calcite. Ordering of the impurities in (0001) layers is energetically favourable with respect to the disordered solid solution at low temperatures and intermediate compositions, but the ordered phase is still unstable to demixing. We calculate the solvus and spinodal lines in the phase diagram using a sub-regular solution model, and conclude that many Ca1-xCoxCO3 mineral solid solutions (with observed compositions of up to x=0.027, and above x=0.93) are metastable with respect to phase separation. We also calculate solid/aqueous distribution coefficients to evaluate the effect of the strong non-ideality of mixing on the equilibrium with aqueous solution, showing that the thermodynamically-driven incorporation of cobalt in calcite (and of calcium in spherocobaltite) is always very low, regardless of the Co/Ca ratio of the aqueous environment.

Nutrição mineral e escleromorfismo foliar de grupos funcionais e comunidades vegetais savânicas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tropical soils with high aluminum concentrations cause oxidative stress in two tomato genotypes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Micronucleus frequency in children exposed to biomass burning in the Brazilian Legal Amazon region: a control case study

Background: The Amazon represents an area of 61% of Brazilian territory and is undergoing major changes resulting from disorderly economic development, especially the advance of agribusiness. Composition of the atmosphere is controlled by several natural and anthropogenic processes, and emission from biomass burning is one with the major impact on human health. The aim of this study was to evaluate genotoxic potential of air pollutants generated by biomass burning through micronucleus assay in exfoliated buccal cells of schoolchildren in the Brazilian Amazon region. Methods: The study was conducted during the dry seasons in two regions of the Brazilian Amazon. The assay was carried out on buccal epithelial cells of 574 schoolchildren between 6-16 years old. Results: The results show a significant difference between micronucleus frequencies in children exposed to biomass burning compared to those in a control area. Conclusions: The present study demonstrated that in situ biomonitoring using a sensitive and low cost assay (buccal micronucleus assay) may be an important tool for monitoring air quality in remote regions. It is difficult to attribute the increase in micronuclei frequency observed in our study to any specific toxic element integrated in the particulate matters. However, the contribution of the present study lies in the evidence that increased exposure to fine particulate matter generates an increased micronuclei frequency in oral epithelial cells of schoolchildren.

Heavy metals in vegetables and potential risk for human health

Ingestion of vegetables containing heavy metals is one of the main ways in which these elements enter the human body. Once entered, heavy metals are deposited in bone and fat tissues, overlapping noble minerals. Slowly released into the body, heavy metals can cause an array of diseases. This study aimed to investigate the concentrations of cadmium, nickel, lead, cobalt and chromium in the most frequently consumed foodstuff in the Sao Paulo State, Brazil and to compare the heavy metal contents with the permissible limits established by the Brazilian legislation. A value of intake of heavy metals in human diets was also calculated to estimate the risk to human health. Vegetable samples were collected at the Sao Paulo General Warehousing and Centers Company, and the heavy metal content was determined by atomic absorption spectrophotometry. All sampled vegetables presented average concentrations of Cd and Ni lower than the permissible limits established by the Brazilian legislation. Pb and Cr exceeded the limits in 44 % of the analyzed samples. The Brazilian legislation does not establish a permissible limit for Co contents. Regarding the consumption habit of the population in the Sao Paulo State, the daily ingestion of heavy metals was below the oral dose of reference, therefore, consumption of these vegetables can be considered safe and without risk to human health.

Toxic and essential elements in blood from delivering women in selected areas of Sao Paulo State, Brazil

This study was designed to evaluate the degree of environmental contamination and possible exposure of pregnant women to toxic elements in seven selected areas of Sao Paulo State, Brazil. The overall median concentration of Mo in maternal blood was 0.53 mu g L(-1), highly significant differences found between sites (p < 0.0001). Cd was found to be low overall - 0.09 mu g L(-1) (0.01-0.58 mu g L(-1)) - with mothers from the Coastal and Rural 1 sites having the highest levels (p < 0.016). Median Hg concentration was 0.60 mu g L (1) (0.06 mu g L (1)-4.35 mu g L (1)); median Pb level was 16.2 mu g L (1) (3.5-57.7 mu g L(-1)) and no differences between sites were observed for both metals. Median Mn level was 16.7 mu g L(-1) (7.0-39.7 mu g L(-1)), being highest in Urban 2 site (p < 0.016). Concentrations of maternal Co were found to range between 0.06 mu g L(-1) and 1.1 mu g L(-1) (median 0.25 mu g L(-1)) and As level was 0.60 mu g L(-1) (0.10-3.8 mu g L(-1)) overall, with no statistical significance between sites for Co and As. Median Se concentrations were found to be 64 mg L(-1) (36-233 mu g L(-1)), with the highest median levels found in Urban 3 site; site differences were statistically significant (p < 0.0001). Correlation for each element (between paired maternal and cord blood) was measured only in Rural site 1; significant correlation was shown for Hg, Pb, Mn and Co (p < 0.05). These findings may be interpreted as indicating low environmental contamination in Sao Paulo State, Brazil. These findings could also indicate that pregnant women have little or no contact with pollutants, possibly due to awareness campaigns carried out by public health practitioners.

Impact of Sahara dust transport on Cape Verde atmospheric element particles

The objectives of this study were to (1) conduct an elemental characterization of airborne particles sampled in Cape Verde and (2) assess the influence of Sahara desert on local suspended particles. Particulate matter (PM10) was collected in Praia city (14°94'N; 23°49'W) with a low-volume sampler in order to characterize its chemical composition by k0-INAA. The filter samples were first weighed and subsequently irradiated at the Portuguese Research Reactor. Results showed that PM10 concentrations in Cape Verde markedly exceeded the health-based air quality standards defined by the European Union (EU), World Health Organization (WHO), and U.S. Environmental Protection Agency (EPA), in part due to the influence of Sahara dust transport. The PM10 composition was characterized essentially by high concentrations of elements originating from the soil (K, Sm, Co, Fe, Sc, Rb, Cr, Ce, and Ba) and sea (Na), and low concentrations of anthropogenic elements (As, Zn, and Sb). In addition, the high concentrations of PM measured in Cape Verde suggest that health of the population may be less affected compared with other sites where PM10 concentrations are lower but more enriched with toxic elements.